The accumulation of static electrical charges on photographic films and photographic papers has long been a serious problem in the photographic arts. These charges arise from a variety of factors during the manufacture, handling and use of radiation-sensitive, image-recording materials. For example, they can occur on photographic sensitizing equipment and on slitting and spooling equipment, and can arise when the paper or film is unwound from a roll or as a result of contact with transport rollers. The generation of static is affected by the conductivity and moisture content of the photographic material and by the atmospheric conditions under which the material is handled. The degree to which protection against the adverse effects of static is needed is dependent on the nature of the particular radiation-sensitive element. Thus, elements utilizing high speed emulsions have a particularly acute need for antistatic protection. Accumulation of static charges can cause irregular fog patterns in a photographic emulsion layer and this is an especially severe problem with high speed emulsions. Static charges are also undesirable because they attract dirt to the photographic recording material and this can cause repellency spots, desensitization, fog and physical defects.
To overcome the adverse effects resulting from accumulation of static electrical charges, it is conventional practice to include an antistatic layer in radiation-sensitive elements. Typically, such antistatic layers are composed of materials which dissipate the electrical charge by providing a conducting pathway. A large number of different materials have been proposed heretofore for use in antistatic layers of photographic elements. For example, U.S. Pat. No. 584,862 (issued June 22, 1897 to Eastman) describes the addition of potassium nitrate to a gelatin layer on the film support to prevent static discharges. Further, U.S. Pat. No. 3,754,924 (issued August 28, 1973 to DeGeest et al) relates to photographic elements having antistatic layers comprising a fluorinated surfactant and solid water-insoluble discrete particles of a matting agent, such as silica.
In U.S. Pat. Nos. 3,850,642 (issued Nov. 26, 1974 to Bailey, Jr. et al) and 3,888,678 (issued June 10, 1975 to Bailey, Jr. et al), radiation-sensitive elements are disclosed which have adjusted surface impact charging characteristics due to the incorporation of a charge control agent in surface layers. Useful charge control agents include cationic fluorinated surfactants. The described elements can also contain soluble salts, e.g. chlorides, nitrates, etc.
Radiation-sensitive elements provided with antistatic layers as described in the art have suffered from one or more significant disadvantages. For example, in certain instances, the antistatic layer has provided inadequate protection against static for high speed emulsions, such as those used in phototypesetting papers. Hence, there has been an unacceptable level of defects in such elements caused by static discharge. Clearly, there is a need in the art for antistatic compositions which provide improved protection from static for radiation-sensitive elements.